EP0672455B1 - Device for wet classifying - Google Patents

Abstract

An assembly classifies a mixt. of solids suspended in liq. into coarse and fine prods. The assembly incorporates a classifying rotor (1) within an outer housing (2) and incorporating a sepn. passage (6, 7). The novelty is that each sepn. passage (6, 7) spirals from an eccentric suspension input section (8, 9) to a coarse particle outlet (10, 11) on the outer circumference of the classification rotor. A classified particle diversion channel (12, 13) extends radially from the sepn. passage (6, 7) to a central fine classified outlet (14) passage. The inlet passage (8, 9) is eccentrically transposed w.r.t. the main axis of rotation.

Description

The invention relates to a device for wet classification a solid mixture suspended in a liquid in coarse and fine goods, according to the Preamble of claim 1.

Wet classifiers of the type required can can be used for different purposes and products. A particularly interesting area of application is Use of such a wet classifier in Grinding circuit of a wet grinding plant, in the suspensions with a relatively high solids content and / or relatively high Fines share are processed. In such cases it is desirable to have that suspended in a liquid and solid mixture coming from a mill in Coarse material (coarse material fraction) and fine material (fine material fraction) to classify, the fines fraction obtained in further processed as desired or as finished goods can be deducted while the the still not containing enough comminuted solids Coarse material fraction for a new shredding process the or a mill can be returned can.

A device for wet classification in the preamble The type of claim 1 presupposes, for example the DE-PS 31 27 599. In this Trap is central or coaxial in a classifying rotor feed area for the rotor axis of rotation solid mixture to be classified, from which from an essentially radial separating channel to a coarse material discharge opening provided on the outer circumference of the rotor leads. One wall of the radial Separation channel is formed by a kind of tongue the one partition to approximately parallel to it Fine material deflection channel forms and in an outer Deflection edge ends around which the fines content of the solid mixture deflected and over the deflection channel in one that is eccentric to the central feed area Fine material discharge channel, which in a fine material container attached under the rotor flows. In the practical implementation of the Wet classifying in this device is the one to be separated Solid mixture, however, only a relatively short one Response time for the desired separation into coarse material and fines through centrifugal force, so that especially with relatively highly viscous solid mixtures (Liquid suspensions) an insufficient Classification efficiency is achieved.

The invention is therefore based on the object Device for wet classification in the preamble of To create claim 1 required type by with relatively low energy requirements and also with relative highly viscous liquid-solid mixtures (Suspensions) an optimal classification of the feed material in coarse and fine goods with a special high efficiency can be guaranteed.

This object is achieved by the in the license plate of the specified features solved.

Advantageous refinements and developments of Invention are the subject of the dependent claims.

In this wet grading device according to the invention the or each separation channel extends - in plan viewed from the classifying rotor - from the feed feed channel up to the coarse material discharge opening spiral in this classifying rotor, while the fine material deflection channel, in which the separated from the solid mixture Fines share against the centrifugal force inwards is directed radially to the coaxial to the central Fine material discharge channel aligned with the axis of rotation. In relation to this central fine material discharge channel is the feed material feed channel in the classifying rotor compared to the axis of rotation (and thus also compared to the Fine material discharge channel) eccentrically offset.

In numerous attempts related to the present invention have been carried out be confirmed by the form and above all by the length of each separation channel (in the circumferential direction of the classifying rotor) the separating effect and thus the Classification efficiency of this new wet classifier optimally to be processed Solid mixture can be adjusted. This optimal Classification can also be used for liquid-solid mixtures or suspensions are guaranteed that a have a relatively high viscosity, for example of> 100 mPa s and also with solids contents of> 10%, as is the case with the wet grinding systems described at the beginning is often the case. Especially in the latter The good classification efficiency that can be achieved proves to be related as particularly advantageous in terms of on energy savings, because so far for example, the entire regrind several successive Crushing passes was, while due to the achievable according to the invention good separation effect is essentially insufficient crushed coarse material another crushing process (to the desired grain size) got to.

The length and design of each separation channel in the classifying rotor can the cheapest response time of the separating solid mixture can be adjusted. This can, for example, with a spiral separation channel take place over a partial circumference of the Classifying rotor or over a circumferential area of the Classifying rotors extend approximately from 360 ° and more can. Another possibility in influencing the separation or classification efficiency can also be achieved if the clear cross section of or each spiral-shaped separation channel itself continuously expanded from the inside out. At this Design of the separation channel can be any suitable Cross-sectional shape are used; especially however, an approximately rectangular cross section is preferred, its long rectangular sides essentially run at right angles to the central axis of rotation. On this way you can the radially outer wall a corresponding gradient (slope the spiral) in the direction of the coarse material discharge opening issue, which makes ejection particularly clog-free of the coarse material on the outer circumference of the classifying rotor is supported. There is also the radially inner wall each separation channel so shaped and spiral trained to reach a certain diameter to ensure that what is to be separated Well enough for a predetermined time Centrifugal force is exposed. Only when the coarse, heavy good particles separated to the outside are, this inner wall of the separation channel inwards or is diverted inwards in order to enough fine portions of the solid mixture divert inside and radially inwards to the fine material discharge channel to lead.

Another advantageous embodiment of the invention can be achieved if the clear cross section of the Coarse material discharge opening is adjustable. This gives is another way of coarse material discharge to influence and any tendency to constipation counteract. But this can also be achieved that the clear cross section of each coarse material discharge opening is periodically changeable, i.e. if those clear cross section as required and if necessary by intervention and control from the outside periodically can be expanded or reduced.

As explained in more detail using exemplary embodiments there are still several advantageous training opportunities to both Classification efficiency as well as throughput to influence this wet classifier for example, by using only a single spiral Separation channel or at least two such Separation channels in a cross-sectional plane of the classifying rotor are trained; in addition, the classifying rotor only a single approximately disc-shaped rotor body with at least one spiraling Separation channel or several directly one above the other, assembled into one unit, approximately disk-shaped rotor body, each with at least a spiral formed therein Have separation channel.

With each type of training of the classifying device according to the invention and in particular that rotatably arranged therein Classifying rotor becomes the one to be classified Solid mixture as a liquid suspension with a certain overpressure is fed to the feed material feed channel. Because the total feed quantity is larger than that carried out on the outer circumference of the rotor Coarse material subset (coarse material fraction) becomes one fines exposed to less centrifugal influence deflected into the fine material deflection channel and inevitably radially inwards over the centrally arranged there axial fine material discharge channel discharged. The Device can also be operated so that at least Lower part of the housing - depending on the application - a negative pressure (Vacuum) or maintain an overpressure becomes.

Fig.1

ein vereinfachte Vertikalschnittansicht der erfindungsgemäßen Naßklassiervorrichtung mit vertikaler Achse;

Fig.2

eine Querschnittsansicht durch Vorrichtungsgehäuse und Klassierrotor bei einer Ausführungsart des Klassierrotors mit zwei Trennkanälen;

Fig.3

eine ähnliche Querschnittsansicht wie Fig.2, jedoch bei einer Ausführungsform des Klassierrotors mit nur einem Trennkanal;

Fig.4

eine vereinfachte Vertikalschnittansicht der Naßklassiervorrichtung mit schräggestellter Achse.

The invention is explained in more detail below with reference to the drawing. Show in this largely schematic drawing

Fig. 1

a simplified vertical sectional view of the wet grading device according to the invention with a vertical axis;

Fig. 2

a cross-sectional view through device housing and classifying rotor in one embodiment of the classifying rotor with two separation channels;

Fig. 3

a cross-sectional view similar to Figure 2, but in one embodiment of the classifying rotor with only one separation channel;

Fig. 4

a simplified vertical sectional view of the wet grading device with an inclined axis.

A first embodiment of the invention Wet classification device will be explained with reference to FIGS. 1 and 2. This device is used for separating or classifying a solid mixture suspended in a liquid in a coarse and a fine fraction, assuming that the wet classifier Is part of a wet grinding plant and that in Liquid suspended solid mixture as comminution product from one that also belongs to the grinding plant Mill stems.

A major component of this wet classifier is a classifying rotor 1 in a fixed housing 2 rotatably mounted about a central axis of rotation 3 (in bearings 4) and driven by a motor 5 can, which will be discussed in more detail later becomes. The classifying rotor 1 contains in this embodiment - As shown in Fig.2 - two worked into it similarly or uniformly trained Separation channels 6, 7, which - in plan view of the classifying rotor 1 viewed (Fig.2) - each from a feed feed channel 8 or 9 up to a coarse material discharge opening 10 or 11 on the outer circumference of the classifying rotor 1 extend approximately in a spiral. The clear cross section each spiral separation channel 6, 7 expanded - as can be clearly seen in Fig. 2 - continuously from the inside to the outside. Furthermore, when viewed the horizontal cross section of the classifying rotor 1 in Figure 2 - preferably approximately in the outer circumferential area of the classifying rotor 1 the inner spiral wall 6a and 7a of each separation channel 6, 7 in a deflection section 6a 'or 7a'. From here leads from everyone Separation channel 6, 7 a separate fine material deflection channel 12 or 13 to a common axial fine material discharge channel 14, which is approximately in the form of a bore centrally or coaxially to the central axis of rotation 3 in the classifying rotor 1 is incorporated. The fine material deflection channels 12, 13 lead thus approximately from the associated separation channel 6 or 7 radial to this fine material discharge duct 14. The already axial feed feed channels mentioned above 8, 9 are - as Figure 2 also clearly shows - indeed also arranged in the area of the central axis of rotation 3, however with respect to this axis of rotation 3 and thus opposite the central fines discharge channel 14 eccentrically transferred.

In the previously described version of each separation channel 6, 7 within the classifying rotor 1 is in the area between the through the respective deflection section 6a ' or 7a 'formed deflection to the fine material deflection channel 12 or 13 and the associated coarse material discharge opening 10, 11 in the transverse direction of the classifying rotor 1 expanded separation space 15 and 16 formed.

The clear cross section of each spiral separation channel 6, 7 is preferably an approximately rectangular cross section trained whose long rectangular sides (parallel to the plane of Figure 2) essentially run at right angles to the central axis of rotation 3. This clear cross section of each spiral separation channel 6, 7 is radially inward through the already inner spiral wall 6a or 7a mentioned above and radially outwards through an outer spiral wall 6b and 7b, which are approximately parallel to the axis of rotation 3 run. Here, the outer spiral wall 6b or 7b directly to the preferably support-shaped Coarse material discharge opening 10 or 11. The light Cross section of the coarse material discharge opening 10, 11 each Separation channel 6 or 7 is expediently adjustable. This Adjustability can be achieved in any meaningful way be, both when the classifying rotor is at a standstill as well as during operation. At the in Fig.2 illustrates the embodiment one side of each coarse material discharge opening 10, 11 on one Side delimited by an approximately wedge-shaped bar 17, which are adjustable in their circumferential direction is that the associated coarse material discharge opening 10 or 11 in its width (in the circumferential direction) accordingly can be enlarged or reduced. By appropriate If necessary, constructive measures can be taken also ensure that the clear cross section each coarse material discharge opening 10 or 11 periodically can be enlarged or reduced, for example after each rotor revolution or after a predetermined one Number of rotor revolutions, each from the outside forth and / or with appropriate control in each case by means of a suitable adjustment linkage, by means of a bell crank, Cam control or the like. Can happen, wherein this periodic changeability if necessary provided in combination with the wedge-shaped bar 17 can be.

In the example illustrated in FIG. 2 with two roughly spiral separation channels in one The cross-sectional plane in the classifying rotor 1 is the two Separation channels 6, 7 in each rotor half (rotor semicircle) of equal size and of the same design, whereby each separation channel 6, 7 extends over a partial circumferential area of the classifying rotor 1 extends from approximately 180 °. As is further evident from the above explanations already results largely from each separation channel 6, 7 a separate feed material feed channel 8 or 9, a separate coarse material discharge opening 10 or 11 and a separate fine material deflection channel 12 or 13 assigned; two separation channels 6, 7 and the associated Fine material deflection channels 12 or 13 is, however, a common Central fines discharge channel 14 assigned.

The classifying rotor 1 can now, depending on the desired Throughput only an approximately disc-shaped rotor body or - as illustrated in Fig.1 - several arranged directly one above the other to form a unit assembled, approximately disc-shaped rotor body 1a, 1b, 1c ... 1n, each with at least one formed therein spiral separation channel (in the example the 1 and 2 with two such separation channels 6, 7). In any case, the classifying rotor 1 is on upper end of the housing 2 via a hollow shaft 19 in the bearings 4 rotatably mounted. In this hollow shaft 19th a feed material inlet pipe 20 is arranged, which over a suitable sealing system 21 with an upper feed supply device 22 is connected and the accordingly, this feed material feeder 22 with each feed material feed channel 8 or 9 in the classifying rotor 1 connects, for example by the in Fig.1 indicated branch pipes 23. In the illustrated in Fig.1 Execution of the classifying rotor 1 with several rotor bodies arranged directly one above the other 1a, 1b ... 1n are the separation channels (e.g. 6, 7 in Fig.2) all rotor bodies parallel to each other from the common feed feeder 22 (via the Inlet pipe 20) can be loaded with feed material.

The classifying rotor 1 is via its hollow shaft 19 as well a suitable drive connection, for example in Form of a belt drive 24, expedient from the drive motor 5 driven at variable speed.

The essentially closed housing 2 is with the feed material feeder 22 already mentioned its upper end and with a coarse material outlet 25 and a fine material outlet 26 approximately in the area of its lower one Provided at the end. The housing 2 itself is also in a cylindrical upper part 2a, which the classifying rotor 1 surrounds with a corresponding radial distance, and divided into an approximately funnel-shaped lower part 2b, whose funnel wall - as shown in Fig.1 - itself narrowed to the coarse material outlet or material outlet nozzle 25. Furthermore, this conical funnel wall of the lower part 2b from one of the fines discharge channel 14 of the Classifying rotor 1 connecting the fine material outlet 26, passes through the inclined fine material discharge pipe 27, the upper, inner end of the housing over a suitable Seal or labyrith seal 28 with the together with the classifying rotor 1 rotating fine material discharge channel 14 communicates. Depending on the mode of operation and the application of this wet classifier it may also be appropriate to the coarse material outlet 25 and the fines outlet 26 each have an additional discharge aid, preferably in the form of suitable conveyors assign. In the example in FIG. 1 it is assumed that the coarse material outlet 25, for example Pump 29 and the fine material outlet 26 also a pump 30 are assigned; instead of such a feed pump could also be a screw conveyor, a discharge lock or the like.

For easier cleaning and control for those inside the housing housed device parts can also be useful if this housing 2 with a Cover 2c is provided, for example with the help one attached to the upper end of the upper part 2a Hinge 31 can be opened and opened, whereby a locking bracket 32 can ensure the housing 2 close tightly, so that, for. B. also under Vacuum or under pressure or even under an inert gas atmosphere can be worked.

The feed material feeder mentioned above can also formed by any suitable conveyor will. In the example in FIG. 1 it is assumed that this feed material feed device 22 also through a suitable feed pump is formed. Hereby can be the feed material, i.e. the one suspended in a liquid Solid mixture that in coarse (Coarse material fraction) and fine material (fine material fraction) classified should be, with the feeding of the classifying rotor 1 can be abandoned via the inlet pipe 20.

In the embodiment of the classifying rotor illustrated in FIG. 2 1 with the spiral-shaped incorporated into it Separation channels 6, 7 is also assumed that this Classifying rotor 1 - when looking at the local one Floor plan or cross-sectional view - to the left is driven in rotation. However, it can be multiple here be appropriate, also the possibility of an opposite Direction of rotation (to the right in Fig. 2) around) to provide, for example, a better Cleaning, for example, in the area of the coarse material discharge openings 10, 11 and / or the separation channels 6, 7 supported can be.

A variant of the above and in particular with reference to Figure 2 illustrated first embodiment results from Fig.3. After that is otherwise largely the same as in the first embodiment constructed classifying rotor 1 'in the considered cross-sectional plane with only one provided spiral-shaped separation channel 36, which - in Contrary to the separation channels 6, 7 in Fig.2 - about a circumferential area of the classifying rotor 1 'of approximately extends about 360 ° (possibly even more). This separation channel 36 can otherwise approximately similar manner (only adapted to the larger circumference) be designed as above has been described in particular with reference to FIG. Accordingly, this leads from spiral Separation channel 36 a fine material deflection channel 37 in turn central, axial fine material discharge channel 14, during a for this purpose, eccentrically offset, axially extending feed material feed channel 8 for feeding the to be classified Solid mixture at the radially inner beginning of the spiral separation channel 36 provides. On the outer circumference this classifying rotor 1 'is accordingly only a single coarse material discharge opening 10 is present again by a wedge-shaped bar 17 or the like. in their clear width can be adjusted.

Regardless of whether only one in the classifying rotor 1 or 1 ' only spiral separation channel 36 or at least two such separation channels 6, 7 are provided, it can many applications of this wet classifier be expedient, a device for supplying additional liquid to the inner wall of the or each Provide separation channel. In the examples of Fig.2 and 3 is for this purpose in the area of each separation channel 6, 7, 36 an axially formed in the classifying rotor 1 or 1 ' Liquid supply channel 38 with one in the direction of Rotor transverse circumferential bore 39 provided, each on the associated inner wall 6a, 7a or 36a of the corresponding separation channel 6, 7, 36 opens out. The supply of the additional liquid to the corresponding Feed channels 38 can, for example, also through the hollow shaft 19 with the help of a corresponding Liquid line happen. By feeding an additional liquid at the points mentioned in many cases the selectivity during the Classification process can still be improved.

Assuming in particular based on the Fig.1 is that the central axis of rotation 3 and thus also the central axis of this classifier aligned vertically is, with an essentially symmetrical design the device housing 2, it may for some Applications can also be advantageous, the invention Wet classifier with more or less more inclined or inclined to the vertical Execute device and axis of rotation 3 '. A such an example is illustrated in Figure 4. How to this vertical sectional view reveals, differs this embodiment compared to First embodiment described above largely only by a certain adjustment of the housing 2 ', while the rotatably mounted and drivable therein Classifying rotor 1 can be completely identical and can work as in the previous examples. Accordingly, the device housing 2 ' again a cylindrical upper part 2'a and one funnel-shaped lower part 2'b, but in this case not conical-symmetrical (as in Fig.1), but funnel-shaped on one side can be trained. Here, the Coarse material outlet 25 'and the fine material outlet 26' - like Fig.4 shows - arranged relatively close to each other be.

• Durch eine variable Drehzahl des Klassierrotors 1, 1' sowie durch eine verschiedene Anzahl von scheibenartigen Rotorkörpern im Klassierrotor kann die Höhe der Fliehkraft beeinflußt werden, die auf das zu trennende Feststoffgemisch einwirkt.
• Durch die Wahl des Durchmessers des Klassierrotors 1, 1' kann zum einen die Länge der einzelnen Trennkanäle 6, 7, 36, und damit die Verweilzeit des Feststoffgemisches in diesen Trennkanälen, als auch das notwendige Gefälle zum Austragen des Grobgutes beeinflußt werden (die Fliehkrafteinwirkung auf das zu trennende Feststoffgemisch wird größer bei zunehmendem Durchmesser).
• Der Verlauf des Gefälles (Spiralsteigung) an der äußeren Spiralwandung 6b bzw. 7b der Trennkanäle 6, 7, 36 beeinflußt die Eigenförderung im zugehörigen Trennkanal 6, 7, 36 sowie auch die Größe der Fliehkräfte während des Klassiervorganges. Dies kann bei Produkten wichtig sein, die leicht zum Ansetzen und Aufseparieren neigen und deshalb meistens ein größeres Gefälle und/oder eine entsprechende Gleitbeschichtung benötigen.
• Das Verhältnis zwischen der Breite und der Höhe jedes - vorzugsweise rechteckigen - Trennkanales 6, 7, 36 beeinflußt ebenfalls die Strömung, die Verweilzeit und die Weglänge der zu klassierenden Gutteilchen im zugehörigen Trennkanal.
• Die Durchsatzmenge des zu klassierenden Aufgabegutes (Feststoffgemisches) beeinflußt ferner die Strömung (laminar oder turbulent) und die Verweilzeit im jeweiligen Trennkanal, aber auch die jeweilige Trenngrenze, d. h. das Verhältnis zwischen Grobgutmenge und Feingutmenge.
• Der lichte Querschnitt der Grobgut-Austragöffnungen 10, 11 am äußeren Ende (Außenumfang des Klassierrotors) des Trennkanales beeinflußt vor allem den Anteil des auszutragenden Grobgutes und damit auch die Trenngrenze für die Grobgutfraktion. Somit können durch die Anordnung von Grobgut-Austragsöffnungen an verschiedenen Positionen (am Außenumfang des Klassierrotors) verschiedene Fraktionen bestimmt und erfaßt werden.
• Die konstruktive Länge jedes Trennkanales 6, 7, 36 (z. B. über nur einen Teilbereich des Rotorumfangs oder über wenigstens 360° des Rotorumfangs) sowie die Anzahl und relative Zusammenordnung dieser Trennkanäle im Klassierrotor bzw. in den zusammengebauten Rotorkörpern beeinflussen ebenfalls vor allem die Zeit, in der die Fliehkraft auf das zu trennende Feststoffgemisch einwirken kann.

The above description of the various design options of this wet classification device according to the invention clearly shows that this device can be optimally adapted to both different solid mixtures or product types (in each case liquid suspensions) and different local conditions. In particular with regard to the desired wet classification function or work, this device according to the invention can be optimally set for a wide variety of products and classification tasks using the following parameters, which can also influence one another:

• A variable speed of the classifying rotor 1, 1 'and a different number of disk-like rotor bodies in the classifying rotor can influence the amount of centrifugal force which acts on the solid mixture to be separated.
• The choice of the diameter of the classifying rotor 1, 1 'can, on the one hand, influence the length of the individual separation channels 6, 7, 36, and thus the residence time of the solid mixture in these separation channels, and also the gradient required for discharging the coarse material (the action of centrifugal force on the solid mixture to be separated becomes larger with increasing diameter).
• The course of the slope (spiral slope) on the outer spiral wall 6b or 7b of the separation channels 6, 7, 36 influences the self-promotion in the associated separation channel 6, 7, 36 and also the size of the centrifugal forces during the classification process. This can be important for products that tend to attach and separate and therefore usually require a larger slope and / or an appropriate sliding coating.
• The ratio between the width and the height of each - preferably rectangular - separation channel 6, 7, 36 also influences the flow, the dwell time and the path length of the good particles to be classified in the associated separation channel.
• The throughput of the feed material to be classified (mixture of solids) also influences the flow (laminar or turbulent) and the dwell time in the respective separation channel, but also the respective separation limit, ie the ratio between the amount of coarse material and the quantity of fine material.
• The clear cross section of the coarse material discharge openings 10, 11 at the outer end (outer circumference of the classifying rotor) of the separating channel influences above all the proportion of the coarse material to be discharged and thus also the separation limit for the coarse material fraction. Different fractions can thus be determined and arranged by arranging coarse material discharge openings at different positions (on the outer circumference of the classifying rotor).
• The structural length of each separation channel 6, 7, 36 (e.g. over only a partial area of the rotor circumference or over at least 360 ° of the rotor circumference) as well as the number and relative arrangement of these separation channels in the classifying rotor or in the assembled rotor bodies also primarily affect the Time in which the centrifugal force can act on the solid mixture to be separated.

Claims (15)

1. Device for wet classification of a mixture of solids suspended in a fluid into oversize material and fine material, containing a classification rotor (1) which can be driven in rotation about a central axis of rotation (3, 3') in a stationary housing (2, 2') and has at least one dividing channel (6, 7, 36) constructed therein which extends from a feed material delivery channel (8, 9) to an oversize material discharge opening (10, 11) on the outer periphery of the classification rotor and from which a fine material deflection channel (12, 13, 37) is led to an axial fine material discharge channel (14) in the region of the axis of rotation, characterised in that the dividing channel (6, 7, 36) - considered in plan view of the classification rotor (1) - extends spirally from the feed material delivery channel (8, 9) to the oversize material discharge opening (10, 11), whilst the fine material deflection channel (12, 13, 37) extends radially with respect to the fine material discharge channel (14) which is aligned coaxially with the central axis of rotation (3, 3'), the feed material delivery channel (8, 9) being offset eccentrically with respect to the axis of rotation.
2. Device as claimed in Claim 1, characterised in that each spiral dividing channel (6, 7) extends over at least a part of the peripheral region of the classification rotor (1).
3. Device as claimed in Claim 1, characterised in that the spiral dividing channel (36) extends over a peripheral region of the classification rotor (1') of at least approximately 360°.
4. Device as claimed in Claim 1, characterised in that the internal cross-section of each spiral dividing channel (6, 7, 36) widens continuously from the interior towards the exterior, an approximately rectangular cross-section being preferably constructed in which the long sides of the rectangle extend substantially at right angles to the axis of rotation (3, 3').
5. Device as claimed in Claim 4, characterised in that each spiral dividing channel (6, 7, 36) has a widened dividing chamber (15, 16) in the region between the deflection point (6a', 7a') to the fine material deflection channel (12, 13, 37) and the oversize material discharge opening (10, 11).
6. Device as claimed in Claim 1, characterised in that the internal cross-section of the oversize material discharge opening (10, 11) is adjustable.
7. Device as claimed in Claim 1, characterised in that in a cross-sectional plane in the classification rotor (1) at least two approximately spirally extending dividing channels (6, 7) are constructed, each having associated with it a separate feed material delivery channel (8, 9), a separate oversize material discharge opening (10, 11) and a separate fine material deflection channel (12, 13) but a common fine material discharge channel (14).
8. Device as claimed in Claim 1, characterised in that the classification rotor (1) has an approximately disc-shaped rotor body which is rotatably mounted by way of a hollow shaft (19) at one end of the housing (2, 2'), and in the hollow shaft is disposed a feed material inlet pipe (20) which connects a feed material delivery arrangement (22) to the (each) feed material delivery channel (8, 9) in the classification rotor (1).
9. Device as claimed in Claim 1, characterised in that the classification rotor (1) has a plurality of approximately disc-shaped rotor bodies (1a, 1b, 1c ... 1n), which are disposed immediately above one another and are assembled into one unit and each have at least one spiral dividing channel (6, 7, 36) constructed therein, and is rotatably mounted at one end of the housing (2, 2') by way of a hollow shaft (19) which connects a feed material delivery arrangement (22) to the (each) feed material delivery channel (8, 9) in the classification rotor (1), wherein the dividing channels (6, 7) of all rotor bodies can be supplied with feed material parallel to one another and from the common feed material delivery arrangement (22).
10. Device as claimed in Claim 8 or 9, characterised in that the classification rotor (1) can be driven at variable speed.
11. Device as claimed in Claim 1, characterised in that an arrangement (38, 39) for delivering additional fluid is provided on the inner wall (6a, 7a, 36a) of each dividing channel (6, 7, 36).
12. Device as claimed in Claim 1, characterised in that the substantially closed housing (2, 2') which is provided with a feed material delivery arrangement (22), an oversize material outlet (25) and a fine material outlet (26) has a cylindrical upper part (2a, 2'a) which surrounds the classification rotor (1) with a radial clearance as well as a hopper-shaped lower part (2b, 2'b) which narrows towards the oversize material outlet and of which the hopper wall has passing through it a fine material outlet pipe (27) which connects the fine material discharge channel (14) to the fine material outlet.
13. Device as claimed in Claim 12, characterised in that at least the lower part (2b) of the housing can be operated with overpressure or underpressure.
14. Device as claimed in Claim 12, characterised in that additional aids to discharge in the form of conveying arrangements (29, 30) are associated with the oversize material outlet (25) and the fine material outlet (26).
15. Device as claimed in Claim 1, characterised in that the internal cross-section of each oversize material discharge opening (10, 11) can be varied periodically.

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